[PATCH tip/core/rcu 01/20] rcu: Remove unnecessary spinlock in rcu_boot_init_percpu_data()

[Paul E. McKenney]

From: Lihao Liang <lianglihao@xxxxxxxxxx>

Since rcu_boot_init_percpu_data() is only called at boot time,
there is no data race and spinlock is not needed.

Signed-off-by: Lihao Liang <lianglihao@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
 kernel/rcu/tree.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 491bdf39f276..66c73a214cff 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3636,12 +3636,9 @@ static void rcu_init_new_rnp(struct rcu_node *rnp_leaf)
 static void __init
 rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
 {
-	unsigned long flags;
 	struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
-	struct rcu_node *rnp = rcu_get_root(rsp);
 
 	/* Set up local state, ensuring consistent view of global state. */
-	raw_spin_lock_irqsave_rcu_node(rnp, flags);
 	rdp->grpmask = leaf_node_cpu_bit(rdp->mynode, cpu);
 	rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
 	WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != 1);
@@ -3649,7 +3646,6 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
 	rdp->cpu = cpu;
 	rdp->rsp = rsp;
 	rcu_boot_init_nocb_percpu_data(rdp);
-	raw_spin_unlock_irqrestore_rcu_node(rnp, flags);
 }
 
 /*
-- 
2.5.2